This invention relates to a tailored blank article and a manufacturing method thereof, which is manufactured by a tailored blank obtained by welding a plurality of blanks, and, for example, is applied to an article used at the position where the inside and the outside are partitioned or an article having a portion for partitioning the inside and the outside, such as a dashboard panel of an automobile.
A dashboard panel of an automobile is a partition article for partitioning the inside and the outside since it partitions an engine room to be exposed to the outside air and a car room to be cut off from the air. As disclosed in Japanese Utility Model Laid-open No. Sho 59-172678, in a conventional dashboard panel, a lower panel made of a thick plate and an upper panel made of a thin plate are joined together by a spot welding.
This kind of dashboard panel is manufactured by pressing a thick plate blank and a thin plate blank into predetermined shapes to produce the lower panel and the upper panel, joining these panels by the spot welding, performing a waterproofing to a space between these panels, and coating an entire body.
When manufacturing an article for a car body of the automobile other than the dashboard panel, which is used at the position where the inside and the outside of the car room are partitioned, by spot welding a plurality of panels produced by the blanks, it was conventionally manufactured by undergoing the same process as that of the aforesaid dashboard panel.
According to this conventional technology, the spot welding is performed after a plurality of the blanks are subjected to the pressing to manufacture a plurality of the panels in predetermined shapes, which makes it necessary to prepare a press die for each blank, thus causing the disadvantage that its cost becomes high. Further, since the panels between a plurality of spot welding portions which are scattered about are not joined together, it is necessary to perform an extra waterproofing in order to prevent a formation of rust by an entering of the waterdrop thereinto, which causes the disadvantage that the productivity becomes difficult to be increased.
An object of the present invention is to provide a tailored blank article and a manufacturing method thereof, which is capable of reducing the number of the press dies compared with the conventional art and making it unnecessary to perform the extra waterproofing in order to prevent the formation of rust.
A tailored blank article according to the present invention is manufactured by using two blanks with these overlapped end portions joined together by a mash-seam welding and pressed as at least a part of material for manufacturing, and a portion made of the two blanks makes a partition portion for partitioning the inside and the outside.
In this tailored blank article, since the overlapped end portions of the two blanks are joined by the mash-seam welding, a pressing into a predetermined shape is performed after the blanks are joined by the mash-seam welding. Therefore, it is unnecessary to prepare a press die for each blank. Further, even if a portion made of the two blanks makes a portion for partitioning the inside and outside, the blanks are joined together without leaving any space therebetween by the mash-seam welding, which makes it unnecessary to perform an extra waterproofing in order to prevent a formation of rust.
Moreover, in the tailored blank article, the blanks are joined together by the mash-seam welding so that higher joining strength can be obtained than in a spot welding, and further, an overlap margin of the end portions can be reduced more than in the spot welding so that the weight reduction and the improvement of material yield can be achieved.
In the tailored blank article, when the two blanks are a thick plate blank and a thin plate blank and the mash-seam welding is performed while the end portion of an outer surface of the thick plate blank to be exposed to the outside is overlaid on the end portion of an inner surface of the thin plate blank, the thin plate blank may be bent until the inner surface of the thin plate blank is made flush or almost flush with an inner surface of the thick plate blank.
Thereby, even if the two blanks are the thick plate blank and the thin plate blank which differ in thickness, the inner surfaces of these blanks are made flush or almost flush with each other, and hence the inner surfaces thereof can be attaching surfaces for attaching other parts.
Further, the tailored blank article according to the present invention is manufactured by using two blanks with these matched end portions joined together by a laser welding and pressed as at least a part of material for manufacturing, and a portion made of the two blanks make a partition portion for partitioning the inside and the outside.
In the tailored blank article, since the matched end portions of the two blanks are joined by the laser welding, a pressing into a predetermined shape is performed after the blanks are joined by the laser welding. Therefore, it is unnecessary to prepare a press die for each blank in this tailored blank article, too. Further, even if a portion made of the two blanks makes a portion for partitioning the inside and outside, the blanks are joined together without leaving any space therebetween by the laser welding, which makes it unnecessary to perform an extra waterproofing in order to prevent a formation of rust, similarly to the case of the mash-seam welding.
Moreover, in the tailored blank article, the blanks are joined together by the laser welding so that higher joining strength can be obtained than in a spot welding, and further, unlike the spot welding, it is unnecessary to overlap the end portions of the blanks so that the further weight reduction and the improvement of material yield can be achieved.
In the tailored blank article, when the two blanks are a thick plate blank and a thin plate blank and respective outer surfaces to be exposed to the outside of the thick plate blank and the thin plate blank are made flush or almost flush with each other, the thin plate blank may be bent until an inner surface of the thin plate blank is made flush or almost flush with an inner surface of the thick plate blank.
Thereby, even if the two blanks are the thick plate blank and the thin plate blank which differ in thickness, the inner surfaces of these blanks are made flush or almost flush with each other, and hence the inner surfaces thereof can be the attaching surfaces for attaching other parts.
In the tailored blank article by both of the mash-seam welding and the laser welding as described above, when a connection part is provided, which is connected to at least one of an outer surface and the inner surface of the two blanks over a welding portion, a portion in the connection part which corresponds to the welding portion is made to be spaced from the welding portion.
Thereby, when the coating is performed onto the surface connected with the connection part in order to ensure durability, after the connection of the connection part, the welding portion by the mash-seam welding and the welding portion by the laser welding can be securely coated.
A method for manufacturing the tailored blank article according to the present invention, which has at least a portion made of the thick plate blank and the thin plate blank as a partition portion for partitioning the inside and the outside, comprising the steps of: joining the end portion of the thick plate blank and the end portion of the thin plate blank while the inner surface of the thin plate blank is overlaid on the outer surface of the thick plate blank to be exposed to the outside by a mash-seam welding, pressing these blanks, bending the thin plate blank until the inner surface of the thin plate blank is made flush or almost flush with the inner surface of the thick plate blank, and thereafter coating at least one of the outer surface and the inner surface of the thick plate blank and the thin plate blank including the mash-seam welding portion.
In this method for manufacturing the tailored blank article, the blanks are subjected to the pressing into the predetermined shape after they are joined by the mash-seam welding, it is unnecessary to prepare the press die for each blank. Further, the blanks are joined together without leaving any space therebetween by the mash-seam welding, which makes it unnecessary to perform the extra waterproofing in order to prevent the formation of rust. Moreover, the blanks are joined together by the mash-seam welding with higher joining strength than in the spot welding, and further, the overlap margin of the end portions of the blanks can be reduced in the mash-seam welding than in the spot welding, so that the weight reduction and the improvement of material yield can be achieved.
Further, in this method for manufacturing the tailored blank article, when the inner surface of the thin plate blank is overlaid on the outer surface of the thick plate blank to be exposed to the outside to perform the mash-seam welding, the inner surface of the thin plate blank is bent until it is made flush or almost flush with the inner surface of the thick plate blank, and hence the inner surfaces thereof can be the attaching surfaces for attaching other parts.
Furthermore, the method for manufacturing the tailored blank article according to the present invention, which has at least a portion made of the thick plate blank and the thin plate blank as the partition portion for partitioning the inside and the outside, comprising the steps of: joining the matched end portions of the thick plate blank and the thin plate blank with the respective outer surfaces of these blanks made flush or almost flush with each other by the laser welding, then pressing these blanks, bending the thin plate blank until the inner surface of the thin plate blank is made flush or almost flush with the inner surface of the thick plate blank, and subsequently coating at least one of the outer surface and the inner surface of the thick plate blank and the thin plate blank including the laser welding portion.
In this method for manufacturing the tailored blank article, the blanks are subjected to the pressing into the predetermined shape after they are joined by the laser welding, and therefore it is unnecessary to prepare the press die for each blank similarly to the case of the mash-seam welding. Further, the blanks are joined together without leaving any space therebetween by the laser welding, which makes it unnecessary to perform the extra waterproofing in order to prevent the formation of rust. Moreover, the blanks are joined together by the laser welding with higher joining strength than in the spot welding, and further, unlike the spot welding, it is unnecessary to overlap the end portions of the blanks in the laser welding, so that the further weight reduction and the improvement of material yield can be achieved.
Furthermore, in this method for manufacturing the tailored blank article, when the laser welding is performed with respective outer surfaces of the thick plate blank and the thin plate blank made flush or almost flush with each other, the thin plate blank is bent until the inner surface of the thin plate blank is made flush or almost flush with the inner surface of the thick plate blank, and hence the inner surfaces thereof can be the attaching surfaces for attaching other parts, similarly to the case of the mash-seam welding.
In the method of manufacturing the tailored blank article by both of the mash-seam welding and the laser welding as described above, when the connection part is provided, which is connected to at least one of the outer surface and the inner surface of the thick plate blank or the thin plate blank over the welding portion, the connection part is connected to the surface of the thick plate blank and the thin plate blank to which the connection part is connected, while the portion to be connected over the welding portion is spaced from the welding portion, and then the coating is performed.
Thereby, when the coating is performed to ensure durability onto the surface of the thick plate blank and the thin plate blank to which the connection part is connected after the connection of the connection part, the mash-seam welding portion and the laser welding portion can be securely coated. Thus, the formation of rust from the welding part can be effectively prevented by a coating film.
Moreover, in the method of manufacturing the tailored blank article by both of the mash-seam welding and the laser welding as described above, the bending of the thin plate blank until the inner surface of the thin plate blank is made flush or almost flush with the inner surface of the thick plate blank may be performed as a part of the working process of the pressing when the joined thick plate blank and the thin plate blank are subjected to the pressing, or may be performed before or after the pressing as a working process which is different from the pressing.
Furthermore, in the tailored blank article and the manufacturing method thereof according to the present invention as described above, the bending of the thin plate blank until the inner surface of the thin plate blank is made flush or almost flush with the inner surface of the thick plate blank means that at a position in the inner surface of the thick plate blank which is a flat surface, the inner surface of the thin plate blank is subjected to the bending to a position which corresponds or almost corresponds to an extension of a straight line from the inner surface of the thick plate blank so that the inner surface of the thin plate blank is made to be a flat surface, and further, at a position in the inner surface of the thick plate blank which is a curved surface, the thin plate blank is subjected to the bending to a position which corresponds or almost corresponds to an extension of a curved line from the inner surface of the thick plate blank so that the inner surface of the thin plate blank is made to be a curved surface.
The blank which can be used in the tailored blank article and the manufacturing method thereof according to the present invention as described above is the one of a metallic plate, especially of a hot rolled steel plate and a cold rolled steel plate. The present invention can be applied to a steel plate having a thickness of 0.7 mm to 3.2 mm, and the steel plate may be without a surface treatment of a plating and the like or may be performed with the surface treatment of a zinc plating and the like. Further, in the present invention, the steel plate with various strength, from a soft steel plate to a high tensile steel plate of 690 MPA class can be used.
Moreover, in the present invention, the coating may be an electrodeposition coating or may be a spray coating.
The present invention can be applied to an article having a part for partitioning the inside and the outside at least in part thereof. An example is a dashboard panel in the case of a car body of an automobile. Other examples of the car body of the automobile are an article made of a front wheel house and a front side frame, an article made of a rear wheel house and a rear side panel inner, and so on.
When the tailored blank article according to the present invention is the dashboard panel, a material of the lower side of the dashboard panel is the thick plate blank and a material of the upper side thereof is the thin plate blank, and the thin plate blank is bent until the inner surface of the thin plate blank, which forms a space inside a car room, is made flush or almost flush with the inner surface of the thick plate blank.
With this dashboard panel, the material of the lower side thereof is the thick plate blank so that strength in this portion can be set so as to bear a load from the front side frame effectively in a collision of the automobiles, and further, the material of the upper side thereof is the thin plate blank so that the entire weight of the dashboard lower panel can be decreased.
Moreover, with this dashboard panel, the respective outer surfaces of the thick plate blank and the thin plate blank, which form an engine room are made uninterrupted or almost uninterrupted by the mash-seam welding or the laser welding, and the thin plate blank is bent until the inner surface of the thin plate blank, which forms the space inside the car room, is made flush or almost flush with the inner surface of the thick plate blank, which makes it possible to prevent a formation of a concave portion and a portion with a difference in level in which the waterdrop is likely to be collected in the outer surface of the engine room side. Thereby, the formation of rust can be prevented from this outer surface to be exposed to the outside.
In order to manufacture the dashboard panel like this according to the manufacturing method of the tailored blank article as described above, the thick plate blank is prepared as the material of the lower side of the dashboard panel and the thin plate blank is prepared as the material of the upper side thereof, the thick plate blank and the thin plate blank are joined together by the mash-seam welding or the laser welding, and the thin plate blank is bent until the inner surface of the thin plate blank, which forms the space inside the car room, is made flush or almost flush with the inner surface of the thick plate blank.
Further, when the tailored blank article and the manufacturing method thereof according to the present invention is applied to the dashboard panel, an example of the connection part connected to at least one of the outer surface and the inner surface of the two blanks over the mash-seam welding portion or the laser welding portion is the front side frame, and other examples are an insulator panel for sound insulation and a reinforcing panel.
Furthermore, the present invention can be applied to articles other than the car body of the automobile, for example, to an outer plate of a small craft, an inner plate of a washing machine tub, an outer plate of a television, an outer panel of a kerosene stove, an outer frame of a personal computer, and so on.